Amazon is buying video game streaming platform Twitch Interactive for €970m in cash as it seeks to expand its presence in gaming.

As video gaming grows into an online spectator sport, gameplay video feeds are becoming increasingly lucrative. Twitch had 55 million unique visitors in July, most of whom went to the site to watch other people play games.

Digital video advertising in the US will reach $5.96bn this year, according to eMarketer, up 41.9pc from 2013.

Amazon already has an in-house gaming studio that makes games, and its Fire TV set top box was designed to attract gamers.